在worker verticle中发出两个请求，并合并两个请求的响应

Question

I have vertx server application where I am getting single client requests and from the server, I need to make two blocking calls. For instance, one call to back-end system A and another call to back-end system B. I am looking to make two concurrent calls to both the systems. I need to wait for the responses from both the calls and then merge two data from both the calls and then send the response back to client. I am unable to figure out how to do this in worker verticle.

Could anyone recommend what would be the best approach in vertx?

Answer 1

This sounds like a good use case for Promises. Give the module vertx-promises a try.

Answer 2

create a CompositeFuture from your launched Futures and handle it normally.

public Future<JsonArray> getEntitiesByIndFields(String keyspace, String entidad, String field1, String field2) {
    Promise<JsonArray> p = Promise.promise();
    // launch in parallel
    Future<JsonArray> f1 = getEntitiesByIndField1(keyspace, entidad, field1);
    Future<JsonArray> f2 = getEntitiesByIndField2(keyspace, entidad, field2);
    CompositeFuture.all(f1, f2).setHandler(done ->
        {
            if (done.failed()) {
                p.fail(done.cause());
                return;
            }
            List<JsonArray> ja = done.result().list();
            JsonArray finalarray = ja.get(0);
            ja.get(1).forEach(jo ->
                { // add one by one, don't duplicate ids
                    long id = ((JsonObject) jo).getLong("id");
                    if (!containsKey(finalarray, id)) {
                        finalarray.add(jo);
                    }
                });
            ;
            p.complete(finalarray); // send union of founds
        });
    return p.future();
}